Women's Health

Hormone-Based Chemotherapy Drugs for Breast Cancer

Hormone-Based Chemotherapy Drugs for Breast Cancer

Hormones are those substances in the body that function as chemical messengers. These hormones affect the actions of the cells and the various tissues that are present at various locations in the body, often reaching out to their target through the bloodstream. The hormones estrogen and progesterone are produced by the ovaries during the premenopausal stage for a woman. Estrogen is known to promote development and also maintenance of the female sex characteristics, as well as the long bone growth, whereas the hormone progesterone plays a vital role in the pregnancy and menstrual cycle for women.


There are certain types of breast cancer that are mostly affected by the hormones that are produced by the body; they are known as ER positive and PR positive breast cancer cells. These cells have receptors that are attached to the estrogen in the body. Estrogen helps these cells to grow and multiply. There are various ways to stop the estrogen from getting attached to these cell receptors. One of the forms of systemic therapy is known as hormone therapy. In this therapy, it reaches out to the cancer causing cells, which can be present anywhere in the body and not just limited to the breast. This hormone based therapy is often used once the surgery is carried out or adjuvant therapy is performed, so as to help reduce the risk of recurrence of cancer. In some cases, this hormone therapy is started prior to conducting the surgery. It is usually used for a period of five years.

To determine if the breast cancer is due to hormone receptors, the doctors would need to conduct certain lab tests of the tumor tissue that was removed during the surgery procedure. If the tumor cell contains estrogen, then the cancer is called estrogen receptor (ER) positive, and if it contains progesterone receptors then the cancer is called progesterone receptor (PR) positive. Most of the hormone based breast cancers are ER based. In some cases, if the breast tumor contains both the hormones, then it is called hormone receptor positive.

Two out of three cases of breast cancer would be reported as hormone receptor positive. For such type of cancer, high levels of estrogen in the body act as a way to grow and develop. Hence, most of the hormone based therapies aim to reduce the estrogen levels or completely stop the production of estrogen from acting on these breast cancer cells.

Common drugs to block the estrogen receptors include:

  • Tamoxifen
  • Tormifene (Farestone)
  • Fulvestrant (Faslodex)

Common drugs to lower the levels of estrogen in the body include:

  • Aromatase inhibitors (AIs), which include Letrozole (Femara), Anastrozole (Arimidex), and Exemestane (Aromasin)
  • Ovarian ablation

Lesser known hormone therapies include:

  • Megestrol acetate (Megace), a progesterone-like drug
  • Androgens (male hormones)
  • High doses of estrogen

Anastrozole (Arimidex):

Anastrozole is used for certain cases of breast cancer in women who have been through the phase of menopause. It also includes those women who have progression of disease after the therapy of tamoxifen. The doctor can also decide when Anastrozole can be used in addition to breast cancer treatment. This medicine is an aromatase inhibitor, and Anastrozole works by lowering the concentrations of blood estradiol. This then leads to the decrease of the growth as well as the size of the cancer tumor.

An individual should not be using Anastrozole if she is allergic to any of the ingredients that are present in the medicine. If the woman has not gone through the phase of menopause, if she is pregnant or planning for pregnancy, if the cancer patient is a man or a child, if one is nursing a baby, or if one is consuming products that contain estrogen, such as certain types of birth control pills or tamoxifen, this medication should not be used. Before you start the medication, inform the doctor if you are allergic to any food or medicine, have been taking any kinds of medications, whether prescribed or non-prescribed, if there has been a past history of the patient or anyone in their family with regards to osteoporosis, problems with the liver, blood vessel problems, or issues of high cholesterol.

Certain medications can tend to interact with Anastrozole; hence, one should notify the doctor if consuming any kind of medicines, vitamins, or supplements. The effectiveness of Anastrozole can be decreased if simultaneously one is consuming products containing estrogen or tamoxifen. Anastrozole should be taken as directed by the doctor, or one can also check the label of the medicine for instructions on usage. Anastrozole should be taken orally with or without food. Even if one starts to feel well, she should continue the medicine and should not discontinue unless recommended by the doctor. Anastrozole leads to lowering of the estrogen levels in the body, which can lead to weakening of the bones, which tend to become softer.

This can then lead to easy fractures, especially of the wrist, hips, and spine. Those women who have a past history of heart blockages can also have a decreased flow of blood to the heart; hence, after taking the medicine, if one has symptoms such as pain in the chest that tends to worsen or shortness of breath, then immediately inform the doctor. Anastrozole should not be given to children, since there is no confirmation of the effectiveness of this medicine on children. The doctor can conduct a routine test of bone density, cholesterol levels, and functioning of the liver, so as to ensure that there are no side effects.

A few of the common side effects of Anastrozole are pain in the muscles, back, bone, and joints, diarrhea, loss of appetite, nausea, vomiting, loss of hair, stomach pain or upset, sudden weight gain, sore throat, symptoms pertaining to flu, and tiredness. If these symptoms worsen, then reach out to the doctor. A few of the severe side effects are swelling of the face, lips, and tongue, changes in the mood that are sudden, burning sensation, blisters, severe case of vomiting and stomach pain, dark colored urine, tingling sensation, numbness, fingers feeling weak, skin lesions, and peeling of the skin.

Goserelin (Zoladex):

Goserelin is very similar to the one that is normally released from the hypothalamus gland, which is situated in the brain. Goserelin is used to treat a number of diseases, such as prostate cancer in men, breast cancer if it develops before or around the same time of menopause phase, and endometriosis. If Goserelin is given regularly as an implant, then it works well every day and helps to reduce the amount of estrogen and testosterone that is produced in the body. By reducing the levels of estrogen in the body, it would help to shrink or damage the cancer cells and avoid it from growing or developing.

However, when the levels of estrogen are suppressed, it leads to thinning or weakening of the bones, or at times, it can result in slow growth, which is a problem for elderly women whose bones do not grow the same as those of children. Goserelin should be given under supervision of the doctor. Goserelin is available in the form of an implant. Before using the medicine, let the doctor know if you are allergic to any contents present in this medicine, if you are pregnant or planning to get pregnant, if one is allergic to any kind of food or medicine, or if one is nursing a baby.

Goserelin is not recommended to be used with certain other drugs, such as saquinavir, ziprasidone, pimozide, bepridil, amifampridine, mesoridazine, terfenadine, and dronedarone. If you are taking the above medicines, then the doctor can decide not to treat you with these and change certain medicines you take. Also, inform the doctor if you are having any medical related issues, such as diabetes, hypercalcemia, hyperglycemia, osteoporosis, alcohol or smoking abuse, history of stroke, heart related issues, having trouble with the urine, and nerve problems that are caused by bone lesions present in the spine.

Goserelin is given as a shot under the skin that is near the stomach. Depending on the severity of the condition and other factors, the doctor can decide to give you this medicine once every 28 days or once in three months’ gap. Even if feeling better, one should continue to receive the treatment unless instructed by the doctor. During the time of the treatment, women should note that there can be certain changes in the menstrual period. It may not be regular as it used to be, or in some cases there would be an absence of periods completely, but this is all part of the treatment.

However, if the menstrual cycle does not start after two to three months of stopping this medicine, or if it is regular during the course of the treatment, then inform the doctor. During the initial phase of the treatment, the symptoms would tend to worsen for a short period of time. Some women may also encounter new symptoms, such as pain in the bone and back, or they can have problems while urinating. However, there is nothing to worry about, since these symptoms would tend to improve within a few weeks of the treatment.

If it gets worse or does not show signs of improvement, then inform the doctor. Along with the positive impact, Goserelin can also lead to unwanted side effects. The common types of symptoms would be irregular vaginal bleeding or light bleeding, menstrual period getting stopped, fainting, anxiety, mood changes or signs of depression, increased facial hair growth, or loss of hair in certain people. The severe form of side effects are pain in the chest, swelling and redness at the injection site, irregular or fast heartbeat, tingling sensation in the hands and feet, skin color changes, pale skin, severe drop in blood pressure, or having trouble while breathing.

Letrozole (Femara):

Letrozole has been primarily used to treat different types of breast cancer in women after menopause. It can be used to treat other medical conditions, as well, which are determined by the doctor. This medicine is an aromatase inhibitor that works by reducing the total amount of estrogen that is primarily produced by the body. This can keep the cancer cells in starvation mode by depriving them of estrogen. Those individuals who are allergic to any of the contents of this medicine and those who have not started menopause should not be using Letrozole.

Before the doctor starts the treatment withLetrozole, let him know if you are pregnant or planning to get pregnant, if you are taking any medicines, whether they are prescribed or non-prescribed, or any kind of vitamins, minerals, or dietary supplements, since they can lead to certain kinds of interactions with this drug. Also, let the doctor know if you are suffering from certain medical conditions, such as liver problems, high cholesterol, current menopause, if one is partaking in hormone replacement therapy. The effectiveness of Letrozole can be decreased if another medicine tamoxifen is also taken together. Letrozole has to be taken orally with or without food.

One needs to take it at a regular schedule so that she benefits the most out of it. Letrozole is known to cause effects of dizziness, and the effects of alcohol, hot weather, or fever can lead to an increase in dizziness in such cases. To prevent this issue, one should sit up or stand slowly, especially during the morning hours. During the first sign of dizziness, try to sit down or lay down as much as possible, and do not exert yourself unnecessarily. The possible side effects of Letrozole are pain in the arms, back, or legs, constipation, loss of appetite, headache, hot flashes, indigestion, pain in the stomach, fluid retention, nausea, tiredness, and irritation at the vagina or vaginal dryness. Severe cases of side effects are allergic reactions to the medicine, such as difficulty breathing, pain or tightness in the chest, chills, sore throat, increase in urination or pain while urinating, excessive vomiting or nausea, and swollen ankles and feet.

Key Takeaways

  • The hormone sensitive breast cancer cells contain proteins that are called hormone receptors, which become activated due to the binding of the hormones.
  • The activated receptors then lead to changes in the expression of certain genes, which can then stimulate cell growth.
  • There are several strategies used for treating hormone based breast cancer.